Sea-glacier retreating rate and climate evolution during the marine deglaciation of a snowball Earth

Abstract

During the Neoproterozoic snowball Earth events, the climate was cold and the oceans were covered by marine ice of ~1000 m thick (sea glacier). Extremely high CO 2 level was required in order to trigger the deglaciation these events. It is unclear how long it would take for the sea-ice cover to be completely ablated after the deglaciation started, and what the physical state of the ocean looked like. Here we use a fully coupled general circulation model, CCSM3, to evaluate the rate of poleward retreating of the marine ice and estimate an upper-bound timescale for the marine deglaciation. It is found that the deglaciation will take at most ~300 to 1500 years, depending on the surface albedo of ice; as the albedo decreases, the deglaciation will be prolonged due to the lower CO 2 level required to start the deglaciation. Such fast calving/melting of sea ice allows a fresh water lid of ~800 m to develop at the end of the deglaciation. • The sea-glacier retreating of snowball Earth is studied using a climate model • The complete ablation of the thick marine ice takes at most ~300 yr to 1500 yr • The elapsed time is longer if the sea-ice albedo is lowered, e.g., by dust • A fresh water lid of hundreds of meters thick would form upon completion